(1) Technical Field
The present invention relates to an eyeglass lens processing apparatus for processing eyeglass lenses.
(2) Related Art
There has been known an eyeglass lens processing apparatus comprising a peripheral edge processing mechanism for grinding a peripheral edge of a lens of an eyeglasses by a peripheral edge processing tool such as a grindstone based on a target lens shape, for example, a shape of a rim of an eyeglass frame. In recent years, moreover, there has also be proposed an apparatus comprising a drilling mechanism for forming a hole to attach a rimless frame such as a two-point frame to a lens by a drilling tool such as an end mill or a drill. In the case that a peripheral edge processing and drilling are executed in a series of processing steps (routine) by such an apparatus, a flow in which all of the processing steps are completed can easily be known visually. For this reason, the drilling is executed after the peripheral edge processing is completed.
In a lens manufactured by plastic (hereinafter referred to as a plastic lens) which is the most general as the material of the lens, processing water is applied from a start of the peripheral edge processing to a completion thereof in order to cool a processed part of the lens. In a lens manufactured by polycarbonate (hereinafter referred to as a polycarbonate lens) having a high thermoplasticity, some heat is required for the peripheral edge processing. For this reason, the processing water is rarely applied in the peripheral edge processing. In order to prevent burning of a processed surface of the lens, however, the processing water is also applied in final finishing to be a final stage for the peripheral edge processing. When water sticks to the polycarbonate lens, however, the processing (cutting) is executed with very difficulty. When the drilling is executed after the peripheral edge processing is completed, therefore, a time required for the drilling is increased, and furthermore, a lifetime of the drilling tool is shortened. Although it is preferable that a step of blowing off the water sticking to the lens should be added after the peripheral edge processing is completed (between the peripheral edge processing and the drilling), a manufacturing cost is increased if a mechanism therefor is incorporated in an apparatus.
As a solving method, it is possible to propose the execution of the drilling before the peripheral edge processing. In the case in which a processing of forming a notch to be a semicircular hole is executed on an edge of a lens as drilling, and furthermore, chambering for rounding off the corner part of the edge of the lens, there is the following problem. More specifically, as described in U.S. Pat. No. 6,336,057 (JP-A-11-309657), it is preferable that a measurement of the shape of the lens to obtain chamfering data for the chamfering should be executed after roughing to be a first stage of the peripheral edge processing. If the notch is formed on the edge of the lens before the roughing, however, there is a possibility that the shape of the lens cannot be measured after the roughing. This problem might occur irrespective of the material of the lens.